The following figure shows a small portion of a long brick wall with patterns made using coloured bricks. Each wall continues this pattern throught the wall. What is the ratio of grey bricks to coloured bricks? Try to give the ratios in their simplest form. 
 
(a) A_15.png
 
Ratio \(=\) i:i
 
(b) A_19.png
 
Ratio \(=\) i:i